| 摘要: | 味覺的辨認屬於一種化學感測的系統，作為評估食品及飲料的用途。因此，味覺具有很重要的應用，像是口服藥物成分的分析、食品及飲料品質的控制甚至是醫學上的診斷等等，所以我們嘗試利用具有良好化學穩定性及光激光性質的金屬有機架構材料(即：[In(OH)bdc]n和MOF-76)來模仿人類舌頭的運作原理。在此研究中，首先藉由溶熱法(類似水熱法)合成金屬有機架構材料，並利用此材料之光激放光(PL)之訊號透過二維的主成分分析(PCA)來識別五種味道：甜、苦、酸、鹹及鮮其相對應之味道分子。主成分是由兩種不同的金屬有機架構材料接觸不同濃度的不同味道分子導致不同的放光性以及放光強度所構成。取其最強放光之波長作為x軸(即主成分1)，而放光強度與味道分子溶液濃度之間的關係式之斜率作為y軸(即主成分2)，來譜出主成分分析之圖形。第二則是藉由放光強度結合味道τ尺度作為味道的定量。此實驗之感測時間為12小時，而感測濃度範圍從10-1M至10-5 M。此金屬有機架構材料作為仿生舌頭之應用具有以下幾點特色：(1) 高分子(即聚丙烯酸)螯合在金屬有機架構材料上，高分子扮演著舌頭味道感受器的角色。當高分子與味道分子進行交互作用後進而影響金屬有機架構材料之發光機制，導致產生不同之放光波長，達到辨識味道分子的效果，(2) 舌頭對於感覺的強度與味道濃度成指數關係成正比，稱之為Weber-Fechner Law of Human Sensing，此與光激光強度關係類似，(3) 以味道τ尺度結合光激光性質對味道作定量探討，(4) 經由模式辨識方式－主成分分析(PCA)來識別五種味道所對應的味道分子。最後我們發展出一種製備金屬有機架構材料薄膜的方法，經由將含有金屬有機架構及高分子之反應液塗佈在基材上，使其揮發後即可作為感測味道之應用。此法的優點為：薄膜之透明度高、可塗佈於大面積基材上及方便製備等。The sense of taste is a specialized chemosensory system dedicated to the evaluation of food and drink. The taste has important roles in the development of oral pharmaceutical formulation, and the control of food quality. Thus, we propose to mimic the working principle of a human tongue through the use of fascinating luminescent materials of metal-organic frameworks (i.e. [In(OH)bdc]n and Tb(btc) (namly, MOF-76)).In this study, solvothermal method was used to synthesis metal organic frameworks and characterized by POM, FT-IR, PL, TGA and PXRD. We have used the photoluminescence (PL) responses of polyacrylic acid-chelated [In(OH)bdc]n and lanthanide Tb(btc) to demonstrate the applicability of MOF-based biomimetic tongue through: (1) identification of five tastes of sweet, bitter, sour, salty and umami by 2-D PCA to distinguish the corresponding tastants of sucrose, caffeine, citric acid, sodium chloride and monosodium glutamate. The plot of PL emission wavelengths of λ = 344, 436, 347, 394, and 335 nm for sucrose-, caffeine-, citric acid-, sodium chloride-, and monosodium glutamate-adsorbed polyacrylic acid-chelated [In(OH)bdc]n as x-coordinates and the slopes of equations between PL emission intensities and concentrations of tastants: 96.1, 126.9, 70.4, 40.5, and 140.8 for sucrose-, caffeine-, citric acid-, sodium chloride-, and monosodium glutamate-adsorbed MOF-76 as y-coordinates. (2) quantification of the strength of five tastes determined by the relationships between the PL intensity and the τ scale of taste. The detection time is 12 h and the detection range of concentrations is from 10-1 M to 10-5 M in this study.There are several important features of our MOF-based “biomimetic tongue”: (1) poly(acrylic acid) (PAA) on [In(OH)(bdc)]n is implemented to mimic the structural flexibility of taste receptor cells (TRCs), (2) the analogue of the Weber-Fechner Law of Human Sensing that sensation is proportional to the logarithm of the stimulus intensity is observed between the PL emission response of MOF-76 and the concentration of the tastant, (3) the strength of taste can be quantified by the ? scale and the PL emission intensity of MOF-76, both of which are dependent on the logarithmic concentration of the tastant, (4) the tastant is identified and distinguished based on a pattern recognition method (i.e. principal component analysis).Finally, this study have developed a method to fabricate the [In(OH)bdc]n/PAA film by brushing. The advantages of this method were: (1) [In(OH)bdc]n could be easily brushed on surfaces of substrate or cover glass to form a transparent thin film, (2) [In(OH)bdc]n could be also spread evenly on the surfaces, and (3) it is convenient to make [In(OH)bdc]n/PAA film through brushing the resulting solution on substrates. |
